PARTITIONING OF STRIKE-SLIP AND CONVERGENT MOTION BETWEEN EURASIA AND ARABIA IN EASTERN TURKEY AND THE CAUCASUS

The plate motion model NUVEL-1 (De Mets et al., 1990) predicts a strongly oblique component to the convergence between Arabia and Eurasia at the longitude of the Caucasus. Earthquake focal mechanisms suggest that this oblique convergence is partitioned into pure right-lateral strike-slip motion in eastern Turkey and pure shortening by thrusting in the Greater Caucasus. Such partitioning offers an explanation for the apparent eastward continuation of the right-lateral faulting of the North Anatolian fault from Turkey into Iran. From a summation of seismic moment tensors between 1911 and 1991 it appears that most of the right-lateral strike-slip motion in eastern Turkey is accommodated by faulting in large earthquakes, while most of the shortening in the Caucasus appears to occur aseismically.